1. Field of the Invention
The invention is concerned with copper-based alloys.
2. Description of the Prior Art
Recent developments in the preparation and processing of copper-rich Cu-Ni-Sn alloys have led to widespread interest in the application of such alloys for a variety of purposes. Among specific applications are the manufacture of electrical components such as wire, wire connectors, and relay elements as mentioned, e.g., in U.S. Pat. No. 3,937,638, "Method for Treating Copper-Nickel-Tin Alloy Compositions and Products Produced Therefrom," U.S. Pat. No. 4,052,204, "Quaternary Spinodal Copper Alloys," and allowed U.S. Pat. application Ser. No. 685,262, "Method for Making Copper-Nickel-Tin Strip Material" now U.S. Pat. No. 4,090,890. Such applications are largely based on alloy properties such as high strength and formability, good solderability, high electrical conductivity, and low electrical contact resistance.
Early investigations of the Cu-Ni-Sn alloy system such as those described by E. M. wise and J. T. Eash, "Strength and Aging Characteristics of the Nickel Bronzes," Trans. AIME, Institute of Metals Division, volume III, pages 218 - 243 (1934), by E. Fetz, "Uber aushartbare Bronzen auf Kupfer-Nickel-Zinn Basis," Zeitschrift fur Metallkunde, volume 28, pages 350 - 353 (1936), by T. E. Kihlgren, "Production and Properties of Age Hardenable Five Per Cent Nickel-Bronze Castings", Trans. AFA, volume 46, pages 41 - 64 (1938), and by A. M. Patton, "The Effect of Section Thickness on the Mechanical Properties of a Cast Age Hardenable Copper-Nickel-Tin Alloy," The British Foundryman, pages 129 - 135 (April 1962) were directed primarily to casting applications and yielded alloys having moderate strength and high hardness. More recent developments have led to Cu-Ni-Sn alloys having superior strength even in casting applications. For example, U.S. patent application Ser. No. 838,141 discloses Cu-Ni-Sn alloys which contain prescribed amounts of Nb, Ta, V, or Fe and which may be shaped as cast, e.g., in the manufacture of high-strength underwater telephone repeater housings.
It is generally appreciated that a uniformly fine grain structure such as induced, e.g., by hot working of an alloy is conducive to good fracture toughness in the alloy. It is similarly appreciated that such uniformly fine structure is desirable in castings and forgings, i.e. applications which may not involve uniform hot deformation of the alloy.